Some radar based surveillance and tracking systems have been used since the 1940s. Typical radar systems detect, identify and characterize objects at long range, on the ground, in the air, and in space. However, the proliferation of small Unmanned Aerial Vehicles (UAV) or Unmanned Aerial Systems (UAS) has exposed weaknesses in radar-based surveillance. With the proliferation of low-cost, small UAS, a new approach to surveillance, detection, tracking and characterization may be preferred.